Big-brained birds survive better in nature

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Published: 10Jan2007

Birds with brains that are large in relation to their body size live longer than those with smaller brains, according to new research published in the journal Proceedings of the Royal Society B: Biological Sciences today.

Birds with brains that are large in relation to their body size live longer than those with smaller brains, according to new research published in the journal Proceedings of the Royal Society B: Biological Sciences today. McGill researcher Louis Lefebvre (Department of Biology), a co-author of the study, said, "This is the first study that shows a survival advantage to brain size."

The research provides evidence for what scientists call the "cognitive buffer" hypothesis – the idea that having a large brain enables animals to have more flexible behaviour and survive environmental challenges. This theory was first put forward to answer the puzzle surrounding why animals, including humans, would evolve a larger brain, given the "cost" associated with developing and maintaining a larger brain.

The researchers compared the brain size, body mass and mortality rates in over 200 different species of birds from polar, temperate and tropical regions. They found that birds with larger brains relative to their body size survived better in nature than birds with small brains.

"Because many factors affect survival, we took into account as many as we could to identify the unique advantage of brain size," added Lefebvre. The researchers made allowances for factors which may also have accounted for variations in mortality rates, such as migratory behaviour, competition for mates and chick behaviour.

Co-author Tamas Szekely, from the University of Bath, said, "Birds are ideally suited for such a test, as they are one of the only groups of animals for which the relationship between large brains and enhanced behavioural response to ecological challenges is best understood. Our findings suggest that large-brained animals might be better prepared to cope with environmental challenges such as climate change and habitat destruction."

The first author of the paper is Dr. Daniel Sol, a former postdoctoral fellow at McGill, now at the Autonomous University of Barcelona (Spain). Andras Liker, from Pannon University (Hungary), is also part of the team.

The research was funded by grants from the Ministerio de Educación y Ciencia (Spain), the Natural Sciences and Engineering Research Council of Canada and the Hungarian Academy of Sciences.